Tuesday, March 25, 2014

Book Review: Your Personal Paleo Code

Chris Kresser has been a major figure in the ancestral health community for some time now. It's funny to recall that I was actually one of his first readers, back in the early days of his blog when it was called The Healthy Skeptic and the audience was small. Chris's readership rapidly eclipsed mine, and now he's in high demand for his ability to convey ideas clearly and offer practical solutions to important health concerns.

He recently published a book titled Your Personal Paleo Code, which also happens to be a New York Times bestseller. The primary goal of the book is to help you develop a diet and lifestyle that support health and well-being by starting from a generally healthy template and personalizing it to your needs. Let's have a look.

Introduction
Kresser opens with the poignant story of his own health problems, which began with an infectious illness in Indonesia and several courses of antibiotic therapy. After years of struggling with the resulting symptoms, trying a variety of diets, and finally accepting his condition, he was unexpectedly able to recover his health by adopting a personalized Paleo-like diet that included bone broth and fermented foods.

Why Paleo?

Chapter 1 focuses on the rationale for eating a Paleo diet and adopting more "ancestral" lifestyle patterns in key areas. It rests primarily on the following core arguments:

We're sick today. Something ain't right about our current diet and lifestyle.

Early agriculturalists were less healthy than their hunter-gatherer forbears.

Our hunter-gatherer ancestors were tall and healthy.

Contemporary hunter-gatherers are healthy, and their health declines when they modernize.

I accept the central "evolutionary" argument in favor of the Paleo diet, although that argument on its own is somewhat theoretical (it has been tested to some degree and the results are promising). Regarding hunter-gatherer health, in my view the key point is not that they are perfectly healthy-- we know that they almost invariably harbor parasites and infant mortality due to infectious disease is very high-- but rather that they rarely suffer from the conditions that trouble us the most today, such as obesity, diabetes, and cardiovascular disease*.

Kresser is quick to acknowledge that certain contemporary cultures have maintained good health on diets heavy in grains, legumes, and dairy, and that this probably results at least in part from cultural and genetic adaptation to agricultural foods. This is part of his rationale for experimenting with these foods as part of a healthy diet.

One thing that I think could have buttressed this chapter further is more discussion of how modern biomedical research has supported many of the core elements of the Paleo approach, such as eating minimally refined food, higher protein and lower calorie density for weight control, and nuts, fruit, vegetables, and wild-caught fish for overall health. The Paleo diet controlled trials would also have been relevant here. But the book is not really designed to be academic-- it's designed to offer a practical diet and lifestyle strategy for regaining and maintaining health, so let's move on to the next section.

Reset

The core strategy of the book is simple but powerful: start with a baseline diet and lifestyle that's healthy for most people, then tinker intelligently to optimize. If you re-introduce a food and it works for you, great-- you have one less thing to restrict.

There's a lot of good information in these chapters, and none of the complex, "imaginative"** mechanistic arguments that often appear in diet books. I do have a hard time with the liberal use of the word "toxin". I agree that many people benefit from reducing or eliminating gluten (or at least flour-based foods), industrial seed oils, and refined sugar, but it's pretty bold to call them toxic. Many people can probably eat wheat and a moderate amount of refined sugar with impunity, although it's not clear what percentage of the population falls into that category.

Kresser has been, and continues to be, a stalwart defender of the idea that dietary carbohydrate is not inherently unhealthy and can be part of a healthy diet. His recommendations in chapter 6 are consistent with this position, however they recommend a beginning carbohydrate intake between 15 and 30 percent of calories. I'm guessing the rationale for this is that the majority of people will start the diet with weight and/or metabolic issues. Later, the plan allows you to increase carbohydrate intake if it agrees with you and/or if you are highly physically active. I like that he ultimately recommends eating the amount of carbohydrate that works best for you-- not an amount dictated by a rigid theoretical framework.

Rebuild

Chapters 11-17 are my favorite. This is the section that really distinguishes Kresser's book from more canonical Paleo books. It's also the section that has gotten heat from the strict Paleo crowd, because it allows careful departures from the canonical Paleo approach, including the consumption of legumes and dairy. Because of this, some have objected to Kresser's use of the term "Paleo".

As an aside, I used to think I knew what the term "Paleo diet" meant. It means a diet composed of food types that our pre-agricultural ancestors might have eaten, right? So when we learn that humans in the Paleolithic relied heavily on a particular food type, we say "what do we have around the grocery store that resembles that food today-- that's part of the Paleo diet". For example, legumes. There is a large body of evidence that Homo sapiens and even Homo neanderthalensis consumed legumes regularly at a variety of archaeological sites (1), and we know that modern hunter-gatherers continue to consume wild legumes today. Legumes are frequently found at sites of Paleolithic human habitation, they're often cooked, and they're even present in dental plaque (1). Did humans harvest and cook legumes only to use them as mouthwash, or might they have swallowed these calorie-rich seeds? The evidence for wild legume consumption by humans is as strong as it is for any plant food consumed during the Paleolithic. If legumes aren't Paleo, then what is Paleo?

In chapter 11, Kresser describes how to methodically re-introduce foods into your diet to see how you react. I think this kind of empirical approach to designing a diet, when carefully applied, can be very powerful. It addresses the fundamental problem that no single diet is optimal for all individuals. His re-introduction strategy is simple and it doesn't involve any fancy medical tests, but it does tell you how you feel and look when you eat specific foods.

Chapters 12-17 describe Kresser's approach to lifestyle, which includes physical activity, sleep, stress management, pleasure, and social connection. These chapters begin with a "quiz" designed to identify your areas of greatest need. If your score on the quiz is low, it may be an area to focus on.

I particularly enjoyed chapter 12, on cultivating pleasure and connection. Kresser makes the case that we're social animals, and we need frequent, positive social connection to remain healthy and happy. This chapter struck me as wise, and it reminded me of some elements of Mark Sisson's book The Primal Blueprint that I also enjoyed.

Fine-tuning

The rest of the book describes how to further refine your Personal Paleo Code, including experimentation with macronutrient ratios, building in reasonable departures from the diet, and customizing for specific health problems.

Conclusion

The basic premise of the book is simple and sound: start from a generally healthy diet and lifestyle template, and optimize it to maximize health and well-being and minimize inconvenience. I think it's abundantly clear at this point that no single diet is best for all individuals, and a certain amount of tinkering is necessary to optimize a diet. Kresser brings this concept to the mainstream with a Paleo twist. Your Personal Paleo Code fills an important need and will help many people find their own paths to health.

*I don't think Paleolithic humans were particularly tall. Contemporary hunter-gatherers actually tend to be quite short by modern standards (adult males roughly 5'2" to 5'5"). If there are any archaeologists in the audience who want to confirm or deny this, please do, but the impression I've gotten from my reading is that Paleolithic Homo sapiens skeletons tend to be moderately short by modern standards, with occasional exceptions, consistent with most modern hunter-gatherers and non-industrial agriculturalists. There are some instances of taller individuals from archaic Homo such as Homo heidelbergensis, but most archaic Homo skeletons seem to be on the short side from what I can tell.

When you start looking at all of this over 99% of the time of human evolution (& not on HG society proxies of the last 10,000yrs) it makes it harder and harder to fit in legumes TO THE SAME EXTENT, as say, fruit or leafy greens.

In a context and scarcity and survival, there is every reason to believe legumes were God-sends! However, in the modern context presenting the paradox of choice and abundance, going out of your way to include legumes for reasons other than "taste/hedonism" doesn't make much sense (IF you are looking to improve the quality/density of your nutrition). This applies to non legume foods as well that don't make the "Paleo approved list" (whatever that is...).

Making sure to distinguish "searching to optimize" with "what can I get away with?" well help make the conversation less reflective of our personal choices and less entrenched - hopefully more science oriented.

Dan Lieberman's "The Story of the Human Diet" would be the go-to book for this, but I don't have access to it right now. As I recall, modern humans have only recently recovered the height of our Paleo ancestors.

A good comparison may be the Plains Indians, as they lived on a pre-agricultural diet, for the most part:

"The average adult male Plains Indian stood 172.6 centimeters tall -- about 5 feet 8 inches. The next tallest people in the world at that time were Australian men, who averaged 172 centimeters. European American men of the time averaged 171 centimeters tall, and men living in European countries were typically several centimeters shorter."

Contemporary hunter-gatherers tend to have been shunted into resource-poor areas and there just aren't that many of them left. I think a lot of the evidence for hunter-gatherers being tall comes from some skeletal remains but more from European accounts of first contact with North Americans, which consistently described them as extremely tall (5'9"-6'0" kind of range) which was gigantic to Europeans of the time. I'm not an archaeologist, I don't even play one on TV, so you might want to double-check that - but if you're interested, I think that's where the "tall hunter-gatherer" assertion came from. Otherwise I think hunter-gatherers tend to show the same wide height distribution as modern industrialized people. There were short dudes and there were tall dudes. Depends which dudes you dig up.

Hunter-gatherers today value legumes as a food source, presumably due to their relatively high content of calories, protein, and micronutrients. For example, the tsin bean is one of the most valued foods for the !Kung San people. These are not fallback foods for the !Kung San, but desirable foods that are considered a cornerstone of the diet.

Hi Tucker and Spughy,

The assertion that HGs were tall depends on isolated examples that I feel don't represent the majority of the evidence I've seen.

The example of "tall" plains Indians is only 5'8" for an adult male, and it is notable for the fact that the population was considered exceptionally tall for the time. The average adult male American of European descent today is nearly 5'10".

I read "The Story of the Human Body" and enjoyed it quite a bit, however it doesn't provide support for the assertion that Paleolithic HGs were tall.

There are HG diets whose dietary staples are either from tubers, animals that fly, live on land or in water. It makes sense that this is the case for a whole host of factors.

How many HG populations do you know that subsist primarily on legumes?!Kung San are 1 example of legume consumption, not empirical evidence of legumes being on the same standing as other dietary staples (such as those mentioned above). Also, legumes aren't their staple but 'only' their 2nd or 3rd most prominent dietary element (likely reflecting their nutritional 'status').

If you have multiple examples of legume consumption as dietary staples of HG societies I'd love to read up on them (really).

Also, legumes could be useful in capacities other than nutrition (medicine or art for e.eg, - art because of the colorful compounds some legumes abound in). I grant you that this last point is somewhat speculative but not implausible nor novel.

My understanding is that native Americans engaged in extensive agriculture prior to contact with the Spanish. Grains and beans were a staple part of the diet. The population fell precipitously after the introduction of European diseases (and reciprocal introduction of syphilis to Europe) and farming decreased over the next 100 or so years. The English immigrants who first settled New England helped themselves to recently vacated cleared land that was no longer being tended by native residents who had died in in the past 1-3 years due to recurrent waves of disease. The cities that existed prior to the introduction of epidemic disease were built of wood and are only recently being excavated and explored.

I'm not at all sure that you can use "typical native American" diet has much of a guide for anything anyway, since there was, again, a pretty broad geographic dispersal.

I think you are misinterpreting what chris meant when he claimed that HG's were tall. I assume he meant they were tall relative to their agricultural contemporaries, and that diverging from the paleo diet to an agriculture diet dramatically shrunk the average size of humans. We have since recovered from this and grown taller over time, which could reflect in part our genetic adaptation to a neolithic diet,as well as our increased consumption of animal foods relative to early agriculturists (it's worth noting that asian cultures have recently grown tall since 'westernizing their diet' i.e., increasing their consumption of animal fats and proteins). It is also consistent with the history of homo evolution that we continue to grow taller as a species over time, so our superior height as compared to paleolithic hunter gatherers would not necessarily be related to diet quality. For example modern hunter gatherers have also generally grown taller than their early predecessors, most notably those consuming more animal fats like the Masai and samuburu tribes (who are MUCH taller and stronger than their agricultural cousins, the largely vegetarian Bantu tribes such as the Kikuyu and Wakamba agriculturists.)

One final point is that I believe there is strong evidence (some of which is cited in Nutrition and Physical Degeneration)that hunter gatherer tribes had/have superior bone density and bone health than us.

40-70% seems quite high. I understand that fat is a healthy part of any diet, however I have rarely heard of more than 30% dietary intake of fat. Protein seems to be the name of the game for achieving an optimally healthy diet. I will have to give this book a read to understand further. Thanks for the article.

Long bone lengths of all available European Upper Paleolithic (41 males, 25 females) and Mesolithic (171 males, 118 females) remains have been transformed into stature estimates by means of new regression equations derived from Early Holocene skeletal samples using "Fully's anatomical stature" and the major axis regression technique (Formicola & Franceschi, 1996). Statistical analysis of the data, with reference both to time and space parameters, indicates that: (1) Early Upper Paleolithic samples (pre-Glacial Maximum) are very tall; (2) Late Upper Paleolithic groups (post-Glacial Maximum) from Western Europe, compared to their ancestors, show a marked decrease in height; (3) a further, although not significant, reduction of stature affects Western Mesolithics; (4) no regional differences have been observed during both phases of the Upper Paleolithic; (5) a high level of homogeneity has also been found in the Mesolithic, both in Western and Eastern Europe; (6) the internal homogeneity found during the Mesolithic in Western and Eastern Europe is associated with marked inter-regional variability, with populations of the latter region showing systematically significantly greater stature than their Western contemporaries. Evaluation of possible causes for the great stature of the Early Upper Paleolithic samples points to high nutritional standards as the most important factor. Results obtained on later groups clearly indicate that the Last Glacial Maximum, rather than the Mesolithic transition, is the critical phase in the negative trend affecting Western European populations. While changes in the quality of the diet, and in particular decreased protein intake, provide a likely explanation for that trend, variations in levels of gene flow probably also played a role. Reasons for the West-East Mesolithic dichotomy remain unclear and lack of information for the Late Upper Paleolithic of Eastern Europe prevents insight into the remote origins of this phenomenon. Analysisof regional differentiation of stature, particularly well supported by data from Mesolithic sites, points to the absence of today's latitudinal gradients and suggests a relative homogeneity in dietary, cultural and biodemographic patterns for the last hunter-gatherer populations of Western Europe. Copyright 1999 Academic Press.

The ancestors of modern Europeans arrived in Europe at least 40,000 years before present. Pre- glacial maximum Upper Palaeolithic males (before 16,000 BC) were tall and slim (mean height 179 cm, estimated average body weight 67 kg), while the females were comparably small and robust (mean height 158 cm, estimated average body weight 54 kg). Late Upper Palaeolithic males (8000 6600 BC) were of medium stature and robusticity (mean height 166 cm, estimated average body weight 62 kg). Stature further decreased to below 165 cm with estimated average body weight of 64 kg in Neolithic males of the Linear Band Pottery Culture, and to 150 cm with estimated average body weight of 49 kg in Neolithic females. The body stature of European males remained within the range of 165 to 170 cm up to the end of the 19th century.

About Me

I'm a writer and science consultant with a background in neuroscience and obesity research. I have a BS in biochemistry and a PhD in neurobiology. I'm the author of "The Hungry Brain: Outsmarting the Instincts That Make Us Overeat".

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